Method and unit for feeding blanks to a user machine

Abstract

A method and unit for feeding blanks to a user machine, whereby at least two synchronized pickup heads withdraw the blanks from respective hoppers and feed them to respective conveying pockets moving continuously along a user path of the machine; each blank adheres by suction to a flat conveying surface of the respective pickup head, with a first lateral edge projecting outwards of the flat conveying surface and with a second edge contacting a push tooth projecting from the respective flat conveying surface, and is so inserted inside the respective conveying pocket as to be maintained in a flat configuration between the push tooth and a stop element moving together with the conveying pocket.

What is claimed is:  
     
       1. A method of feeding blanks to a user machine, the method comprising the steps of withdrawing blanks ( 2 ) from a pickup station (S 1 ) by means of a transfer device ( 9 ) having at least one pickup head ( 10 ) movable cyclically through the pickup station (S 1 ) and through an unloading station (S 2 ), the pickup head ( 10 ) having a flat conveying surface ( 28 ) and at least one push tooth ( 30 ) projecting from the flat conveying surface ( 28 ), and the blank ( 2 ) adhering by suction to the flat conveying surface ( 28 ) and being arranged with a respective first lateral edge ( 40 ) projecting from the flat conveying surface ( 28 ) and with a respective second lateral edge ( 39 ) contacting said push tooth ( 30 ); engaging the first lateral edge ( 40 ) of the blank ( 2 ) against a stop element ( 18 ) of a conveying pocket ( 8 ) movable continuously along a user path (P 1 ) of the user machine ( 3 ) extending through said unloading station (S 2 ); detaching the blank ( 2 ) from said flat conveying surface ( 28 ); and pushing the blank ( 2 ), by means of the push tooth ( 30 ), against the stop element ( 18 ) to secure the blank ( 2 ) between the stop element ( 18 ) and the push tooth ( 30 ) and maintain a flat configuration of the blank ( 2 ) until the blank ( 2 ) is fully inserted inside said conveying pocket ( 8 ); the step of detaching the blank ( 2 ) from said flat conveying surface ( 28 ) being performed by engaging at least one end portion ( 41 ) of the blank ( 2 ) along respective engaging means ( 34 ) located alongside said user path (P 1 ) at said unloading station (S 2 ); wherein the method comprises the step of guiding the blank ( 2 ), during insertion of the blank ( 2 ) inside the respective conveying pocket ( 8 ), by engaging said second lateral edge ( 39 ) in sliding manner by means of guide means ( 33 ) facing said engaging means ( 34 ) at said unloading station (S 2 ). 
     
     
       2. A method as claimed in claim  1 , wherein said transfer device ( 9 ) comprises at least two pickup heads ( 10 ) movable cyclically through respective pickup stations and unloading stations (S 1 , S 2 ); each pickup head ( 10 ) inserting the respective blank ( 2 ) inside a respective conveying pocket ( 8 ) to form a succession ( 11 ) of blanks ( 2 ) along said user path (P 1 ). 
     
     
       3. A method as claimed in claim  2 , wherein said two pickup heads ( 10 ) are synchronized with each other. 
     
     
       4. A method as claimed in claim  1 , wherein said user path (P 1 ) is a straight path; said pickup head ( 10 ) being movable along a feed path (P 2 ) tangent to the user path (P 1 ) at said unloading station (S 2 ). 
     
     
       5. A method as claimed in claim  4 , wherein said pickup station (S 1 ) is defined by an open end ( 6 ) of a hopper ( 4 ) containing a stack ( 5 ) of blanks ( 2 ); said feed path (P 2 ) comprising a portion (T) perpendicular to said open end ( 6 ); and said flat conveying surface ( 28 ) of said pickup head ( 10 ) being moved towards said open end ( 6 ) into a position coplanar with a blank ( 2 ) located at said open end ( 6 ). 
     
     
       6. A method as claimed in claim  5 , wherein said transfer device ( 9 ) comprises an oscillating element ( 26 ) for supporting said pickup head ( 10 ); the pickup head ( 10 ) being fitted in rotary manner to the oscillating element ( 26 ). 
     
     
       7. A unit for feeding blanks to a user machine, the unit ( 1 ) comprising at least one conveying pocket ( 8 ) movable continuously along a user path (P 1 ) of the user machine ( 3 ); a transfer device ( 9 ) having at least one pickup head ( 10 ) movable cyclically through a pickup station (S 1 ) to withdraw a respective blank ( 2 ), and through an unloading station (S 2 ), located along said user path (P 1 ), to feed the blank ( 2 ) to said conveying pocket ( 8 ), the pickup head ( 10 ) comprising a flat conveying surface ( 28 ), at least one push tooth ( 30 ) projecting from the flat conveying surface ( 28 ), and suction means ( 31 ) by which the blank ( 2 ) adheres to the flat conveying surface ( 28 ) in such a manner that the blank ( 2 ) has a respective first lateral edge ( 40 ) projecting from the flat conveying surface ( 28 ) and a respective second lateral edge ( 39 ) contacting the push tooth ( 30 ), and said conveying pocket ( 8 ) comprising a stop element ( 18 ) for retaining the first lateral edge ( 40 ) of the blank ( 2 ); and detaching means ( 34 ) for detaching the blank ( 2 ) from said flat conveying surface ( 28 ) while maintaining the blank ( 2 ) secured in a flat configuration between the stop element ( 18 ) and the push tooth ( 30 ); said detaching means ( 34 ) being defined by engaging means ( 34 ) for engaging at least one end portion ( 41 ) of said blank ( 2 ) and detaching the blank ( 2 ) from said flat conveying surface ( 28 ); said engaging means ( 34 ) being located alongside said user path (P 1 ) at said unloading station (S 2 ); wherein the unit comprises guide means ( 33 ) located facing said engaging means ( 34 ) at said unloading station to guide the second lateral edge ( 39 ) of said blank ( 2 ) as the blank ( 2 ) is inserted inside the respective conveying pocket ( 8 ). 
     
     
       8. A unit as claimed in claim  7 , wherein said transfer device ( 9 ) comprises at least two pickup heads ( 10 ) movable cyclically through respective pickup stations and unloading stations (S 1 , S 2 ); each pickup head ( 10 ) inserting the respective blank ( 2 ) inside a respective conveying pocket ( 8 ) to form a succession ( 11 ) of blanks ( 2 ) along said user path (P 1 ). 
     
     
       9. A unit as claimed in claim  8 , wherein said two pickup heads ( 10 ) are synchronized with each other. 
     
     
       10. A unit as claimed in claim  7 , wherein said user path (P 1 ) is a straight path; said pickup head ( 10 ) being movable along a feed path (P 2 ) tangent to the user path (P 1 ) at said unloading station (S 2 ). 
     
     
       11. A unit as claimed in claim  10  and comprising a hopper ( 4 ) containing a stack ( 5 ) of blanks ( 2 ) and having an open end ( 6 ) through which the blanks ( 2 ) are withdrawn and which defines said pickup station (S 1 ); said feed path (P 2 ) comprising a portion (T) perpendicular to said open end ( 6 ); and the flat conveying surface ( 28 ) of said pickup head ( 10 ) being positioned coplanar with said open end ( 6 ) along said portion (T). 
     
     
       12. A unit as claimed in claim  11 , wherein said transfer device ( 9 ) comprises an oscillating element ( 26 ) for supporting said pickup head ( 10 ); the pickup head ( 10 ) being fitted in rotary manner to the oscillating element ( 26 ).